Refactor and improvements for "transactional-updates" module

[meaksh]

What does this PR do?

This PR changes the way the transactional-update module is working internally in order to run Salt actions inside new transactions.

The previous architecture used the Salt SSH approach, using the SSH wrappers, Salt thin and state.pkg in order to execute a Salt action inside a transaction. We found this is a bit problematic, and produce some issues particularly when dealing with complex/fancy states like:

# this is example1.sls

my_test_state:
  module.run:
    - name: state.apply

The above state produce the following error when running in a transactional system:

slem51:~ # salt-call state.apply example1
local:
----------
          ID: test_example1
    Function: module.run
        Name: state.apply
      Result: False
     Comment: Module function state.apply executed
     Started: 10:42:19.295456
    Duration: 71.843 ms
     Changes:   
              ----------
              ret:
                  ----------
                  no_|-states_|-states_|-None:
                      ----------
                      __run_num__:
                          0
                      changes:
                          ----------
                      comment:
                          No Top file or master_tops data matches found. Please see master log for details.
                      name:
                          No States
                      result:
                          False

Summary for local
------------
Succeeded: 0 (changed=1)
Failed:    1
------------
Total states run:     1
Total run time:  71.843 ms

Similarly with this other state, where filerefs appears as missing (will force us to use extra_filerefs for this particular call):

# this is example2.sls

run_test2:
  module.run:
    - name: state.apply
    - mods: tests2

and

# this is tests2.sls

something_test:
  cmd.run:
    - name: date

In this case we are getting:

slem51:~ # salt-call state.apply example2
local:
----------
          ID: run_test2
    Function: module.run
        Name: state.apply
      Result: True
     Comment: Module function state.apply executed
     Started: 10:45:22.012088
    Duration: 89.861 ms
     Changes:   
              ----------
              ret:
                  - No matching sls found for 'tests2' in env 'base'

Summary for local
------------
Succeeded: 1 (changed=1)
Failed:    0
------------
Total states run:     1

What this PR does in order to solve this problems is the following:

1. Use a normal "salt-call" execution instead SSH approach to execute a Salt action inside a new transaction.
2. Make use of concurrent flag to allow execution of the underlying "salt-call" in case of states execution.
3. Implements --no-return-event for "salt-call" to avoid getting duplicated events on the Salt event bus.
4. Solved the above issues about missing filerefs or master top data.
5. Fixed a problem with state.highstate not acting according to concurrent flag described in Salt documentation.

This brings some benefits:

• No need to struggle with "extra_filerefs" for those states that contains references that are not included in the state.pkg.
• More transparent approach. Should cause less troubles and work with complex states.

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

Yes

Please review Salt's Contributing Guide for best practices.

See GitHub's page on GPG signing for more information about signing commits with GPG.

[meaksh]

I notice there are few tests failures, I'm pushing necessary fixes

[meaksh]

@Ch3LL thanks for the review! 👍

I've pushed some of the requested changes and did some comments about the parameter deprecations.

[github-actions]

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When I was created we had a lot of these. The documentation for these
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So what does that have to do with my PR?

I noticed that in this PR there are some files changed that have some of these
issues. So I'm leaving this comment to let you know your options.

Okay, what are they?

Well, my favorite, is that since you were making changes here I'm hoping that
you would be the most familiar with this module and be able to add some other
examples or fix any of the reported issues.

If I can, then what?

Well, you can either add them to this PR or add them to another PR. Either way is fine!

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Whatever approach you decide to take, just drop a comment here letting us know!

Detected Issues (click me)

Check Known Missing Docstrings...........................................Failed
- hook id: invoke
- duration: 1.57s
- exit code: 1
/home/runner/.cache/pre-commit/repo8mv9kx9s/py_env-python3/lib/python3.9/site-packages/distutils_hack/init.py:30: UserWarning: Setuptools is replacing distutils.

warnings.warn("Setuptools is replacing distutils.")

The function 'get_pauses' on 'salt/modules/state.py' does not have a 'CLI Example:' in it's docstring

The function 'apply' on 'salt/modules/state.py' does not have a 'CLI Example:' in it's docstring

The function 'test' on 'salt/modules/state.py' does not have a 'CLI Example:' in it's docstring

Found 3 errors

---

Thanks again!